Install perl via Homebrew. Follow the instructions you see in the Terminal during/after the install. (Speaking namely of this one.)
Install cpanm as you have done two days ago.

Create the ENV_PERL5LIB variable in KM with the paths as shown. It is also extremely helpful that you set up your ENV_PATH variable so that it includes the Homebrew install path. These are for example my paths:
ENV_PATH: /Users/tom/bin:/usr/local/bin:/usr/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin
ENV_PERL5LIB: /Users/tom/perl5/lib/perl5:/usr/local/Cellar/perl/5.26.0/lib/perl5/site_perl/5.26.0
Replace tom with your account name, of course.

Install the modules as required by the script (cpanm <module name>)

OK, here is how I translate that into specific commands.
Please review and confirm/correct.

# Is brew installed as part of the macOS?
# Create bash_profile if it does not exit
touch ~/.bash_profile
# INSTALL PERL if not already installed
# use this rather than the perl that comes with macOS
# How can we check to see if it is already installed?
brew install perl
# INSTALL cpan
brew install cpanm
# INSTALL Required Modules
cpanm Domain::PublicSuffix
cpanm Net::Domain::ExpireDate
cpanm Date::Calc
# SET KM VARIABLES
ENV_PATH: /usr/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin
ENV_PERL5LIB: /usr/local/Cellar/perl/5.26.0/lib/perl5/site_perl/5.26.0

# Is brew installed as part of the macOS?
# Create bash_profile if it does not exit
touch ~/.bash_profile
# INSTALL PERL if not already installed
# use this rather than the perl that comes with macOS
# How can we check to see if it is already installed?
brew install perl
# INSTALL cpan
brew install cpanm
# INSTALL Required Modules
cpanm Domain::PublicSuffix
cpanm Net::Domain::ExpireDate
cpanm Date::Calc
# SET KM VARIABLES (Rev 1)
ENV_PATH: /usr/local/bin:/usr/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin
ENV_PERL5LIB: /Users/<MacUserName>/perl5/lib/perl5:/usr/local/Cellar/perl/5.26.0/lib/perl5/site_perl/5.26.0

No. See here how to install it. BTW, I do not want to force you to use Homebrew. There are other package managers, like MacPorts. So feel free to use whichever you want.

JMichaelTX:

How can we check to see if perl is already installed?

perl is installed on every macOS, as well as ruby and python etc. But if you are using a scripting language regularly I wouldn’t meddle too much with the ones installed by default, because these are going to be used by other programs and maybe even the system itself. In addition the preinstalled versions are rarely up-to-date.

By default non-brewed cpan modules are installed to the Cellar. If you wish
for your modules to persist across updates we recommend using `local::lib`.
You can set that up like this:
PERL_MM_OPT="INSTALL_BASE=$HOME/perl5" cpan local::lib
echo 'eval "$(perl -I$HOME/perl5/lib/perl5 -Mlocal::lib)"' >> ~/.bash_profile